BS 4367-1968 Methods of test for nitric acid《硝酸的试验方法》.pdf

1、BRITISH STANDARD BS 4367:1968 Methods of test for Nitric acidBS4367:1968 This British Standard, having been approved by the ChemicalsIndustry Standards Committee and endorsed by theChairman of the Chemical Divisional Council, was publishedunder the authority ofthe General Council on 21 October 1968

2、BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference CIC/21 Draft for comment 67/8572 ISBN 580 00357 4 Co-operating organizations The Chemicals Industry Standards Committee, under whose supervision this British Standard was prepared, consists of represent

3、atives from the following Government departments and industrial organizations: Board of Trade British Steel Industry Chemical Industries Association* Fertiliser Manufacturers Association Ltd.* Gas Council* Institute of Vitreous Enamellers Institution of Gas Engineers Ministry of Health National Sulp

4、huric Acid Association Royal Institute of Public Health and Hygiene The industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: British Sulphate of Ammonia Fed

5、eration Limited Ministry of Defence, Army Department National Coal Board Pharmaceutical Society of Great Britain United Kingdom Atomic Energy Authority Amendments issued since publication Amd. No. Date CommentsBS4367:1968 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Fore

6、word ii 1 Scope 1 2 Determination of total acidity 1 3 Determination of sulphuric acid content 1 4 Determination of nitrous acid content 2 5 Calculation of nitric acid content 3 6 Determination of combined ammonia content 3 7 Determination of total sulphate content 4 8 Determination of chloride cont

7、ent 5 9 Determination of iron content 6 10 Determination of lead content 7 11 Determination of sulphated ash 8 Figure 1 Pressure pipette 10 Figure 2 Typical device for use in the determination of sulphuric acidcontent 11 Figure 3 Ammonia distillation apparatus 12 Figure 4 Splash head for apparatus f

8、or the distillation of ammonia 13 Figure 5 Tap funnel and double-bulb splash head 14BS4367:1968 ii BSI 12-1999 Foreword This standard makes reference to the following British Standards: BS 612, Nessler cylinders. BS 975, Density-composition tables for aqueous solutions of nitric acid. BS 1647, pH sc

9、ale. BS 1752, Laboratory sintered or fritted filters. BS 1792, One-mark volumetric flasks. BS 1848, Glass condensers. BS 3591, Industrial methylated spirits. BS 3978, Water for laboratory use. BS , Methods of test for sodium hypochlorite solution 1) . The preparation of this British Standard was aut

10、horized by the Chemicals Industry Standards Committee in order to provide methods for the analysis of nitric acid of commercial quality and intended for general industrial use. This standard prescribes methods of test only and should not be used or quoted as a specification defining limits of purity

11、. References to the standard should be in a form of words indicating the methods of test used conform to BS 4367. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a Bri

12、tish Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 14 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This wi

13、ll be indicated in the amendment table on the inside front cover. 1) In course of preparation.BS4367:1968 BSI 12-1999 1 1 Scope This British Standard describes methods of test for commercial nitric acid suitable for general industrial purposes. 2 Determination of total acidity 2.1 Outline of method.

14、 A weighed quantity of the acid is diluted with water and titrated directly with standard sodium hydroxide solution. 2.2 Apparatus. The following apparatus is required: 1) Pressure pipette, as shown in Figure 1. 2) Flask, conical 150 ml capacity, fitted with a glass stopper. 2.3 Reagents. The reagen

15、ts used shall be of a recognized analytical reagent quality. Water complying with BS 3978 2)shall be used throughout. 1) Sodium hydroxide, N standard volumetric solution. 2) Bromophenol blue indicator solution, 0.4 g/l. Warm 0.1 g of bromophenol blue with 3.0ml of0.05N sodium hydroxide solution and

16、5 ml of95 % (v/v) ethanol 3) ; after solution is effected, add 50 ml of 95 % (v/v) ethanol 3)and dilute to 250 ml with water. 2.4 Procedure. Put 3050 ml of water into the flask, carefully dry the neck of the flask and the stopper and ensure that the outside of the flask is thoroughly dry. Replace th

17、e stopper and weigh the flask to the nearest milligramme. Using the pressure pipette transfer about2ml of the sample to the flask, taking care not to allow the pipette to touch the water or sides of the flask. Immediately replace the stopper, rotate the flask to mix the contents and allow to stand f

18、or five minutes. Momentarily withdraw the stopper to adjust the pressure. Carefully wipe the outside of the flask and reweigh to the nearest milligramme. Add a few drops of the bromophenol blue indicator and titrate without delay with the sodium hydroxide until the colour just changes to a true blue

19、. At the end-point, the addition of a further drop of the sodium hydroxide will produce no further change in colour. NOTEFor the highest accuracy it is essential to take into account corrections arising from calibration of the burettes and to correct the volumes of standard sodium hydroxide solution

20、 used for any deviation of temperature from that at which the solution was standardized. Relevant tables for this purpose are given in “Chemical analysis. The working tools”: C. R. N. Strouts, H. N. Wilson, R. T. Parry-Jones, eds., Volume 1, page 222, Clarendon Press 1962. 2.5 Calculation. Total aci

21、dity, calculated as nitric acid, HNO 3 , 3 Determination of sulphuric acid content 3.1 Outline of method. Nitrogen acids are removed by volatilization in a current of hot air and the residual sulphuric acid is titrated with standard sodium hydroxide solution. 3.2 Apparatus. The following apparatus i

22、s required: 1) Conical flask, 300 ml capacity, with a suitable device to aid evaporation. One such device is shown in Figure 2; the mouth of the flask is closed by a loosely fitting, hollow, tapered closure, designed so that heated filtered air may be blown into the flask and the volatile nitrogen a

23、cids allowed to escape. The cup at the top serves as a deflector. 2) Air line, in which filtered compressed air is heated by passing through a coil of metal tubing immersed in boiling water. 2) BS 3978, “Water for laboratory use”. 3) Ethanol may be replaced by industrial methylated spirits, 66 degre

24、es O.P., complying with BS 3591, “Industrial methylated spirits”. It should be noted that the use of industrial methylated spirits is governed by The Methylated Spirits Regulations 1952 (S.I. 1952 No. 2230). where T 1 = volume, in millilitres, of N sodium hydroxide solution used in the titration and

25、 M 1 = mass, in grammes, of sample taken. percentage by mass 6.302T 1 M 1 - =BS4367:1968 2 BSI 12-1999 3.3 Reagents. The reagents used shall be of a recognized analytical reagent quality. Water complying with BS 3978 4)shall be used throughout. 1) Sodium hydroxide, 0.1N standard volumetric solution.

26、 2) Hydrochloric acid, 0.1N non-standardized volumetric solution. 3) Bromophenol blue indicator solution, 0.4 g/l. Warm 0.1 g of bromophenol blue with 3.0 ml of0.05N sodium hydroxide solution and 5 ml of95 % (v/v) ethanol 5)after solution is effected, add 50 ml of 95 % (v/v) ethanol 5)and dilute to

27、250 ml with water. 4) Litmus paper, neutral. 3.4 Procedure. Transfer a suitable quantity of the sample, according to the expected sulphuric acid content, to the flask and place the closure in position. Place the flask in a boiling water-bath in a fume cupboard and connect to the heated, filtered air

28、 supply. Continue passing the air until the escaping air is acid free when tested with the moistened litmus paper. Wash down the closure and the walls of the flask, using about10ml of water and repeat the evaporation. Again wash down with about 10 ml of water and repeat the evaporation. To 50 ml of

29、water add a few drops of the indicator solution and just neutralize it with the hydrochloric acid solution. Use this water to wash down the walls of the flask and the inside of the closure and collect the washings in the flask. Titrate the solution in the flask with the sodium hydroxide solution. 3.

30、5 Calculation. Sulphuric acid content, calculated as H 2 SO 4 , 4 Determination of nitrous acid content 4.1 Outline of method. The nitrous acid is oxidized with excess ceric sulphate solution, and the excess titrated with standard ammonium ferrous sulphate solution. 4.2 Reagents. The reagents used s

31、hall be of a recognized analytical reagent quality. Water complying with BS 3978 4)shall be used throughout. 1) Ammonium ferrous sulphate, 0.1N standard volumetric solution. NOTEThis solution requires restandardization each week. 2) Ceric sulphate, 0.1N non-standardized volumetric solution. To 55 g

32、of dry ammonium ceric nitrate add 50 ml of concentrated sulphuric acid (d = 1.84) and evaporate almost to dryness. Dissolve the residue in approximately N sulphuric acid solution and dilute to 1000 ml with this acid. 3) N-Phenylanthranilic acid indicator solution, 2 g/l. Dissolve 0.1g of N-phenylant

33、hranilic acid in 10ml of N sodium hydroxide solution and dilute to 50ml with water. This solution is stable for about 1 week. 4.3 Procedure. Into a stoppered weighing bottle, weigh to the nearest milligramme, about10g of the sample. Transfer the weighing bottle and stopper to a wide-necked conical f

34、lask containing about 200 ml of water and 25.0 ml of the ceric sulphate solution. Swirl the flask to mix the contents, add 1 drop of the N-phenylanthranilic acid solution and titrate with the ammonium ferrous sulphate solution. At the same time titrate under the same conditions25.0 ml of the ceric s

35、ulphate solution. 4.4 Calculation. Nitrous acid content, calculated as HNO 2 , 4) BS 3978, “Water for laboratory use”. 5) Ethanol may be replaced by industrial methylated spirits, 66 degrees O.P., complying with BS 3591, “Industrial methylated spirits”. It should be noted that the use of industrial

36、methylated spirits is governed by The Methylated Spirits Regulations 1952 (S.I. 1952 No. 2230). where d = relative density aof the sample at room temperature, V 1 = volume, in millilitres, of sample taken and T 2 = volume, in millilitres, of 0.1N sodium hydroxide solution used. a Useful information

37、is given in BS 975, “Density-composition tables for aqueous solutions of nitric acid”. percentage by mass 0.4904T 2 V 1 d - = where T 3 = volume, in millilitres, of 0.1N ammonium ferrous sulphate solution used for the 25.0 ml of ceric sulphate solution, T 4 = volume, in millilitres, of 0.1N ammonium

38、 ferrous sulphate solution used in the determination and M 2 = mass, in grammes, of sample taken. percentage by mass 0.235 T 3 T 4 () M 2 - =BS4367:1968 BSI 12-1999 3 5 Calculation of nitric acid content The nitric acid content is calculated from the following formula. Nitric acid, calculated as HNO

39、 3 , percentage by mass = A 1.29 B 1.34 6 Determination of combined ammonia content 6.1 Outline of method. The combined ammonia present is distilled from an alkaline solution and absorbed in a solution of sulphuric acid. It is then determined spectrophotometrically using the phenoxide-hypochlorite m

40、ethod. 6.2 Apparatus. The apparatus required, as depicted diagrammatically in Figure 3, comprises: 1) Kjeldahl flask, 500 ml nominal capacity (A). 2) Splash head with built-in tap funnel, as detailed in Figure 4 (B). As an alternative to the splash head (B), a separate tap funnel may be used in conj

41、unction with a double-bulb splash head (see Figure 5). 3) Allihn condenser, four bulb, complying with BS1848 6)(C). 4) Expansion bulb, approximate capacity 100 ml, with a delivery tube (D). 5) Conical beaker, nominal capacity 650 ml (E). 6) Photoelectric absorptiometer or spectrophotometer with 2 cm

42、 cells. 7) Eight one-mark volumetric flasks 7) , 50 ml capacity. 6.3 Reagents. The reagents used shall be of a recognized analytical reagent quality. 1) Ammonia-free water. Prepared as follows: Place 500 ml of tap water in a 1 litre round-bottomed flask. Add 1 ml of approximately16N sulphuric acid.

43、Connect the flask to a spray trap and condenser and distil. Collect the distillate in Nessler cylinders, 25 ml at a time, and test each portion with Nessler reagent. When the distillate is free from ammonia, collect it in a glass-stoppered bottle. Removal of ammonia from water can also be accomplish

44、ed in many cases by use of a strong cation exchange resin in the H +form. For most work a satisfactory water can be obtained by shaking 5 litres of distilled water with 10g of a strong cation exchange resin or by passing distilled water through a column of such an ion exchange resin. This water shal

45、l be used throughout. 2) Sodium hydroxide, 300 g/l reagent solution. 3) Sodium hypochlorite reagent solution, 9.0 g/l available chlorine. Prepare daily by dilution with water of a stock sodium hypochlorite solution containing 90120 g/l of available chlorine. Standardize this solution weekly, accordi

46、ng to the instructions given in BS 8) . 4) Sodium phenoxide reagent solution. a) Dissolve 62.5 g of phenol in 18.5 ml of acetone, and dilute to 100 ml with 95% (v/v) ethanol 9)and mix. Store this solution in the dark, preferably in a refrigerator. b) Dissolve 27 g of sodium hydroxide in 100 ml of wa

47、ter. As required, prepare the reagent by mixing 20 ml of each solution and diluting to100 ml with water. 5) Sodium hydroxide, 5N non-standardized volumetric solution. 6) Sulphuric acid, 0.01N non-standardized volumetric solution. where A = total acidity, percentage by mass, calculated as nitric acid

48、, B = sulphuric acid content, percentage by mass and C = nitrous acid content, percentage by mass. 6) BS 1848, “Glass condensers”. 7) BS 1792, “One-mark volumetric flasks”. 8) BS , “Methods of test for sodium hypochlorite solution”. (In course of preparation.) 9) Ethanol may be replaced by industria

49、l methylated spirits, 66 degrees O.P., complying with BS 3591, “Industrial methylated spirits”. It should be noted that the use of industrial methylated spirits is governed by The Methylated Spirits Regulations 1952 (S.I. 1952 No. 2230).BS4367:1968 4 BSI 12-1999 7) Standard combined ammonia solution. Dissolve 0.315 g of ammonium chloride in 1000 ml of water. Immediately before use dilute 10 ml of this solution to 100 ml with water. 1 ml of this diluted soluti